1 (**************************************************************************)
4 (* ||A|| A project by Andrea Asperti *)
6 (* ||I|| Developers: *)
7 (* ||T|| The HELM team. *)
8 (* ||A|| http://helm.cs.unibo.it *)
10 (* \ / This file is distributed under the terms of the *)
11 (* v GNU General Public License Version 2 *)
13 (**************************************************************************)
15 set "baseuri" "cic:/matita/PREDICATIVE-TOPOLOGY/ac_defs".
17 (* Project started Wed Oct 12, 2005 ***************************************)
21 (* ACZEL CATEGORIES: *)
22 (* We use typoids with a compatible membership relation *)
23 (* The category is intended to be the domain of the membership relation *)
24 (* The membership relation is necessary because we need to regard the *)
25 (* domain of a propositional function (ie a subset in the predicative *)
26 (* setting) as a quantification domain and therefore as a category, but *)
27 (* there is no type in CIC representing the domain of a propositional *)
30 record AC: Type \def {
33 aceq: ac \to ac \to Prop
36 definition a \def \lambda A. ac A.
40 inductive eq (A:AC) : ac A \to ac A \to Prop \def
41 | eq_refl: \forall a. acin ? a \to eq A a a.